<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .box1{
            width: 300px;
            height: 300px;
            border: 1px solid red;
            position: relative;
        }
        .box2{
            width: 200px;
            height: 200px;
            border: 1px solid blue;
            position: absolute;
            margin-left: 150px;
            left: -101px;
            margin-top: 150px;
            top: -101px;
        }
    </style>
</head>
<body>
    <div class="box1">
        <div class="box2"></div>
    </div>
    
</body>
</html>